This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 2-keto-3-deoxy-D-manno-octulosonate 8-phosphate phosphatase (KDO8PP) will be compared against a structurally homologous enzyme, 2-keto-3-deoxy-9-O-phosphonononic acid phosphatase (KDN9PP). Both are haloalkanoate dehalogenase superfamily (HAD) phosphatase enzymes from Bacteroides Thetaiotaomicron. KDO8PP and KDN9PP are homologous in primary sequence and three-dimensional structure, and have similar ligands and active sites. Through this analysis, substrate specificity residues will be identified. Then these residues will be swapped from one enzyme to the other to engineer specificity. By analyzing these two similar enzymes, the means of endowing substrate specificity can be identified.